78(mean age : 25 yrs) periodontally healthy volunteers participated in this study. Two maxillary central incisor and one lateral incisor were selected to study. With minimal local anesthesia, guttapercha cone inserted to labial gingival sulcus of selected teeth just after bone sounding with periodontal probe. Metal ball (4mm diameter) attached to palatal fossa of central incisor. Then, periapical radiograph was taken according to long cone paralleling technique. After film scan, labial alveolar bone profile reproduced along interproximal bone and apical ends of gutta-percha cones on computer screen. By utilizing computer program, the distance from height of interproximal bone to the labial bone crest in central incisor-central incisor and central incisor-lateral incisor area was measured and converted to real distance by using vertical length of metal ball on film. After measuring crown length & width of central incisor, the 10 individuals ranked lowest CW/L ratio (crown width/length ratio) and the 10 ranked highest were selected as having a long-narrow(group N), or a short-wide(group W) form of the central incisors. Means of the distance from height of interproximal bone to the labial bone crest of group N, W were calculated and compared by means of independent t-test.

The results were as follows:

1. Mean distance from the height of the interproximal bone to the labial bone crest was 3.5±0.7mm between two central incisor, and 2.8±0.6mm between central and lateral incisor.

2. Mean CW/L ratio of group N was 0.57, and group W was 0.8. Mean distance from the height of the interproximal bone to the labial bone crest of group N was higher than group W in both measured area(measurements of group N, W were 3.9±0.2mm and 3.5±0.2mm between two central incisor, 3.0±0.2mm and 2.8±0.2mm between central and lateral incisor), but there were no statistically significant differences when the groups were compared.

Within the limits of the present study, there was a tendency that subjects with long-narrow teeth have more scalloped alveolar bone profile than subjects with short-wide teeth in upper anterior area, but no statistically significant differences were found.